One of various known types of initiators is constituted by a pair of electrodes joined together via an insulator; a bridge wire connected with these two electrodes and adapted to generate heat when energized; and a capsule accommodating the bridge wire and an explosive able to detonate in response to heat generation of the bridge wire. This type of initiator is disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. H11-301402.
In order to manufacture the above-described type of initiator compactly, the individual components of the initiator must be reduced in size, which results in a reduction in the usable amount of explosive (the amount of explosive that can be charged in the capsule). For this reason, conceivably, when the explosive is ignited for detonation in such a downsized conventional structure, there arises a fear that a desired level of flame propagation energy cannot be obtained in an intended direction.